I. Cross-Reference to Related Application
Reference is made to application Ser. No. 07/989,804, now U.S. Pat. No. 5,327,905 issued Jul. 22, 1994 which is a continuation-in-part of application Ser. No. 07/909,867, now U.S. Pat. No. 5,354,297 issued Oct. 11, 1994 both of common inventorship with the present application. The cross-referenced applications also describe improved catheters and tip orientation or manipulation control systems.
II. Field of the Invention
The present invention is directed generally to an improved catheter navigation or manipulation control system adaptable to any steerable vascular catheter, but particularly for use in the field of cardiac arrhythmia recording and ablation. The invention involves an improved single-knob handle control system that simplifies the control of the highly maneuverable working catheter tip area. The control system allows the operator to hold the control handle and direct the tip of the catheter in multiple directions, i.e., in three-dimensional space, using the same hand to operate the control knob and precisely maneuver the catheter tip. The apparatus is particularly useful in navigating catheter devices with electroded tips in cardiac chambers and around heart valves.
III. Discussion of the Related Art
Certain advantages available with regard to steerable catheter systems have been recognized. Such devices can be inserted into blood vessels or similar bodily areas and their distal end navigated through the tortuous vascular path to reach areas of the body normally inaccessible without surgery. Such navigating catheter devices generally require a certain amount of rigidity, so that the posture of the distal tip can be controlled; but they also need to exhibit a certain amount of flexibility to facilitate intricate navigation of the distal catheter tip. In addition, to facilitate use, steerable catheters ideally should possess the ability both to bend in the plane parallel to the main axis of the catheter and also at the same time to be deflected radially, i.e., in a plane generally perpendicular to that of the main catheter axis so that complete and controlled three-dimensional spatial maneuvering of the tip in, for example, an internal chamber, such as a cardiac chamber, can be realized.
Catheters of the steerable or self-navigating type, having electrode means for monitoring parts of the body, such as for electrically mapping the heart by receiving and transmitting electrical signals related to the operation of that organ to recording signal processing and display devices are also known. The ability to successfully record impulses or signals and from them electrically map the cardiac chambers and valves using flexible catheters having steerable electroded tips has further led to the use of the technique of transcatheter ablation of cardiac tissues that have been identified as the pathways that cause cardiac arrhythmias. This technique has emerged as one of the most important advances in cardiac electrophysiology. Its goal is to destroy the arrhythmogenic tissue without compromising the mechanical or muscular integrity of the cardiac tissues and vessels.
Not long ago, for example, many patients with Wolff-Parkinson-White syndrome or ventricular tachycardia underwent surgical dissection of the arrhythmogenic tissue followed by a painful and prolonged recovery. Introduction of the transcatheter approach has dramatically reduced the suffering and cost of this definitive treatment for many causes of cardiac arrhythmias. The general approach to this procedure initially preferably utilized high energy direct current delivered to the catheter poles, for example, to disrupt the A-V node condition and even to create a complete heart block by ablating the His bundle. More recently, however, radio frequency has replaced high energy direct current as the preferred primary source of energy and the transcatheter approach for cardiac ablation has become an accepted and common procedure and has been used increasingly as the primary mode of treating cardiac arrhythmias. Transcatheter cardiac tissue ablation is more fully discussed in Avitall et al, "Physics and Engineering of Transcatheter Tissue Ablation", JACC, Volume 22, No. 3:921-32. The rapid clinical acceptance of this procedure and the proliferation of physicians engaged in transcatheter tissue ablation has mandated the development of improved steerable catheter devices.
One earlier steerable catheter device is shown in U.S. Pat. No. 4,785,815 to Webster, Jr. That device includes a catheter tube which carries one or more electrodes at its distal tip for sensing membrane potentials within the heart, together with a heating device for ablating at least a portion of the pathway located by the sensing device. That catheter includes a deflection control which allows the introduction of a curvature to the working tip of the catheter; however, any lateral or radial maneuvering of the deflected or bent tip requires rotation of the entire catheter system. Another catheter device which utilizes a single handle-operated deflection wire to produce curvature in the tip is disclosed in U.S. Pat. No. 4,960,134. A turn-limiting proximal adapter for a steerable catheter system which includes a stationary portion and a rotating portion is shown in U.S. Pat. No. 5,185,004 to Lashinski. That device is utilized to rotate a guidewire, to facilitate the performance of an angioplasty procedure.
Electrophysiological catheter ablation procedures, however, are still hampered by the difficulties encountered by the operator in attempting to maneuver the catheter tip to the precise location of the arrhythmogenic tissue. This is primarily due to the limited maneuverability control afforded by prior catheters. Generally, available catheters, even catheters with single deflection wire control, have been characterized by inadequate control of fine movements and have tips that can be deflected only in planes parallel to the main catheter tube other than by rotating the entire device. This makes the process of aligning electrodes with the precise ablation site of interest a long and tedious affair.
The above cross-referenced applications describe a biplanar deflection system which allows control of the lateral movement of the catheter tip as well as controlling deflection in planes parallel to the main catheter tube. That system employs a controllable element or elements which impart both direct deflection by reciprocation of the control element and lateral deflection by the transmission of rotational torque along the control element. Systems in accordance with those inventions can be assembled utilizing a single control wire or a plurality of control wires. These devices greatly enhance control and facilitate maneuvering of the catheter tip in three-dimensional space, reducing the time required in the addressing of cardiac chamber and valve locations, control of the catheter and maneuvering of the catheter tip generally requires the use of both hands by the operator. There clearly remains a definite need for the development of a full control deflection system that can be operated by a handle control which requires but one hand to hold the catheter and to perform the control functions including fine tuning.
Accordingly, it is a primary object of the present invention to provide an improved control system for improving the controlled navigation of flexible catheter tips.
Another object of the invention is to provide a catheter control handle that can be held and the tip control or navigation system operated all with one hand.
Still another object of the invention is to provide a precise yet mechanically simple system to accomplish complete three-dimensional catheter tip control.
Yet a further object of the invention is to enable complete three-dimensional spatial navigation of a catheter tip utilizing a single control knob.
Other objects and advantages of the invention will occur to those skilled in the art based on a review of the illustrations and descriptions herein.